As people have said, blogs work well for promotion IF you have text entries. I've seen a lot of adult blogs that are nothing but pics and links to sponsors. Why even bother, if there's nothing there for the search engine spiders to index?
The other important thing is to make good link trades and get listed in some blog-related lists. One easy way to get recips is to sign your blog up at
Bloglinker and put their script in your side bar. Once that's up, you can visit other blogs with that script and do automatic link trades.
We have a blog category at Blue Wave (see sig).
And
Top Blogs has an adults only category that sends good traffic. They usually don't list blogs unless they have text entries.